Ed Gould wrote:
On Nov 30, 2015, at 5:54 PM, Charles Mills wrote:
----------------SNIP-------------------------------------
With the advent of facility and function indications in
z/Architecture, the technique of trial execution should
be avoided - particularly if a workload may be relocated
to another system in which a facility's instructions
may not be present. In such an environment,
STORE FACILITY LIST EXTENDED (STFLE) or an
instruction's query or test function may provide a
more accurate indication of facilities and functions
that are available on all systems in the computing
environment.
Charles:
While that may have been a "backdoor" way of doing things, I believe IBM
introduced the concept of the SU Bit String which I believe was meant to
be a "programming interface" now if my memory is correct was for
figuring out which FMID (selectable unit) was installed. The interface
was specifically for software that was installed. During that time frame
the only "hardware" that was really installable was the vector facility
(if memory serves me, I could be wrong) and I think there was a SU for
that even. We never had it so I have no first hand knowledge. IBM did
drop that somewhere in the early 1980's(approximately). I know we were
semi celebratory because we were tired of assembling the nuc for some
trivial function like DEMF.
So in the past there was at least one other interface to figure out the
hardware that was installed.
<snip>
The SU Bit String was built by (IIRC) GENERATE causing the IHASUBIT
macro to use other macros. Macros setting zeroes were shipped, to be
replaced by macros that set ones when different components were
installed. Nowhere was hardware directly involved, as this was a
software installation time change,
The SU Bit String had been frozen for quite a while when I came along
and caused IHASUBIT and its associated macros to be removed from the
(then) MVS/ESA SP Version 4 product after System Generation was finally
withdrawn in all its flavors.
--
John Eells
IBM Poughkeepsie
ee...@us.ibm.com
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